AIRWAY MANAGEMENT 101
MANAGEMENT OF THE “ROUTINE”
PEDIATRIC AIRWAY
ANDREW TRIEBWASSER, MD
D E PA R T M E N T O F A N E S T H E S I O L O GY
H A S B R O C H I L D R E N ’ S H O S P I TA L
APRIL 2015
LARYNGEAL ANATOMY
Neonatal larynx and schematic
DEVELOPMENTAL ANATOMY OF THE LARYNX (I)
in infants.....
•
tongue proportionally larger
•
occiput proportionally larger
•
larynx more cephalad
•
epiglottis angled from trachea
•
short, omega-shaped epiglottis
•
vocal folds angled
•
narrowing of cricoid ring
DEVELOPMENTAL ANATOMY OF LARYNX (II)
Larynx more
cephalad in infants
DEVELOPMENTAL ANATOMY OF LARYNX (III) *
A D U LT
I N FA NT
* CLASSIC TEACHING TENET
DEVELOPMENTAL PHYSIOLOGY OF
THE AIRWAY (I)
•
•
•
•
preponderance of type I muscle fibers
obligatory nasal breathing
low apneic threshold
sensitivity genioglossus muscle to halothane
(& presumably sevoflurane)
DEVELOPMENTAL PHYSIOLOGY OF
THE AIRWAY (II)
apneic threshold
obligate nasal breathing
AIRWAY PATENCY IN ANESTHETIZED
CHILDREN
• immobile maxillary block
• mobile mandibular block obstructs
• loss of genioglossus tone (Motoyama)
• adenoidal hypertrophy
• non-invasive maneuvers / CPAP
• artificial airways
AIRWAY MANAGEMENT: SOAP
Suction
Oxygen
Airway Equipment
Pharmacology (implies monitoring)
COMPRESSED GAS CYLINDERS (I)
you open your E cylinder oxygen container by slowly
turning the valve CCW until fully open. The
pressure in the cylinder is 650 psi.
Assuming flow of 4 LPM, how
many minutes of oxygen remain?
COMPRESSED GAS CYLINDERS (II)
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•
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E cylinders contain ~ 660 liters
working pressure ~ 2000 psi
the tank is ~ 1/3 full (220 L)
45 minutes of oxygen remaining
USA - oxygen tanks are green
INTL - oxygen tanks are white
ROUTINE AIRWAY EQUIPMENT
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•
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laryngoscope
breathing bag
oral airways
suction catheter
tonsil-tip suction
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endotracheal tubes
stylets
masks (± LMA)
extra blades
pharmacology
CORRECT PLACEMENT OF ORAL AIRWAYS
Tip just cephalad to angle of
mandible - OPTIMAL
Tip posterior to angle of
mandible - pushes epiglottis
down & worsens obstruction
Tip above angle of mandible kinks the tongue
THE LARYNGEAL MASK
AIRWAY (LMA) CLASSIC *
•initial supraglottic device (SGA)
•peri-laryngeal seal
•steep learning curve
•could provide temporizing
ventilation in “cannot intubate”
•adjunct for intubation ± FOB
Patient wt (kg) LMA size
Cuff vol (ml)
<5
1
4
5-10
1.5
7
10-20
2
10
20-30
2.5
14
30-50
3
20
50-70
4
30
70-100
5
40
* INTRODUCED IN 1987,FAIRLY
WIDESPREAD USE AND ACCEPTANCE
BY EARLY 1990’S
SUPRAGLOTTIC DEVICES – UPDATE (I)
•
well established routine and emergency airway management
1st or 2nd (gastric access channel) generation
• 2nd generation better “2nd seal”* facilitating ↑ PPV
• some protection vs. unexpected regurgitation / aspiration
• Jaannathan N. Pediatric Anesthesia 2-15;25:334 (good review)
•
*
leading edge rests in upper
esophagus, creating a 2nd,
or hypopharyngeal seal
SUPRAGLOTTIC DEVICES – UPDATE (II)
LMA classic
LMA unique
Air-Q
LMA proseal
LMA supreme
I-gel
ENDOTRACHEAL INTUBATION – WHY?
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•
•
•
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ensures airway patency
airway protection
pulmonary toilet
IPPB with FiO2 of 1.0
positioning not supine (especially prone)
KEYS TO SUCCESSFUL ENDOTRACHEAL
INTUBATION
•adequate SOAP prep
•optimize patient position
•adequate mouth opening
•tongue well swept to left
•control of epiglottis
•external manipulation larynx
•watch through the cords
OPTIMIZING PATIENT POSITION
• first described by Jackson 1913
• Bannister & Macbeth “sniffing” 1944
 slight neck flexion & extend a-o joint
• Adnet (2001) MRI criteria – sniffing no better
than simple extension – both better than neutral
 axes are not aligned in sniffing position
(as depicted by the “classic”diagram above)
KEYS TO SUCCESSFUL ENDOTRACHEAL
INTUBATION
•adequate SOAP prep
•optimize patient position
•adequate mouth opening
•tongue well swept to left
•control of epiglottis
•external manipulation larynx
•watch through the cords
MANDIBULAR ADVANCEMENT & LARYNGEAL VIEW
TAMURA M ET AL. ANESTHESIOLOGY 100:598;2004
BURP (backward upward pressure)
better view than mandibular
advancement – best view with BOTH
SUGGESTED LARYNGOSCOPE BLADES
AGE
MILLER
preemie
0
neonate
0-1
newborn – 18 months
1
18 months - 5 years
MAC
WIS-HIPPLE
1
1
1
2
1.5
5 - 12 years
2
2-3
> 12 years
2-3
3
MILLER VS. MAC BLADE IN SMALL CHILDREN
•perception that straight blade lifting epiglottis “better”
•randomized crossover study 1-24 months (n=120)
•ND in 2 groups – restricted view w/either blade may be improved
by switching blades
VARGHESE E. PEDIATRIC ANESTHESIA 2014;24:825
SUGGESTED ETT SIZE BY AGE
AGE
SIZE (ID mm)
DEPTH (cm)
preemie
2.5 – 3.0
7
term < 6 months
3.0 – 3.5
9
6 – 9 months
3.5 – 4.0
10
9 - 18 months
4.0 – 4.5
11
18 – 24 months
4.5
12
3 years
4.5 – 5.0
13
5 years
5.0 – 5.5
15
10 years
6.0 ± cuff
17
14 years
6.5 - 7.0 cuff
18 - 20
HISTORIC RATIONALE FOR UNCUFFED
ETT IN CHILDREN
A D U LT
I N FAN T
PEDIATRIC AIRWAY ANATOMY MAY NOT BE WHAT WE
THOUGHT: IMPLICATIONS CLINICAL PRACTICE & USE CUFFED ETT
•anatomy cited by Eckenhoff 1951 based on cadaver data Bayeux 1897
•questioned by recent bronchoscopic images , CT/MRI imaging of airway
•pediatric airway elliptical, not circular → more circular with age
•AP diameter > transverse diameter – narrowest at level of vocal cords
•no evidence for previously held conical shape in small children
schematic of cuff (green) inflated
in elliptical airway
TOBIAS JD. PEDIATRIC ANESTHESIA 2015;25:9
COMPARISON OF CUFFED AND UNCUFFED
ENDOTRACHEAL TUBES IN YOUNG CHILDREN
KHINE HH ET AL. ANESTHESIOLOGY 86:627, 1997
• 488 pts < 8 years undergoing GETA
 uncuffed size (mm ID) = (age + 16) / 4 OR
 cuffed size(mm ID) = (age/4) + 3 *
age/4 + 4
• appropriate in 99% (vs. 77%) p < 0.001
• advantages - ↓ laryngoscopies, ↓ FGF, ↓ OR anesthetic
• incidence of croup 1.2% vs. 1.3% (ND)
*
MODIFIED BY DURACHER TO AGE/4 + 3.5 (2008)
CUFFED OR UNCUFFED ENDOTRACHEAL TUBES IN PEDIATRIC ANESTHESIA:
SURVEY OF CURRENT PRACTICE IN UK AND NETHERLANDS
SK BOERBOOM. PEDIATRIC ANESTHESIA 2015;25:231
USE OF A CUFFED ETT RAISES OTHER
CONCERNS
• cuff may herniate above cords
• advantage newer spherical shape vs
older elliptical shaped cuffs
• cuff may be over-inflated
• ideal inflation 20-30 cm H2O (devices)
• higher inflation pressure may damage
tracheal mucosa
adjuncts to ensure
appropriate cuff pressure
*
CONFIRMING PLACEMENT OF ETT
ARE
Are we
in WE
? IN?
auscultation of BS
symmetrical chest
movement
listen over stomach
detection of CO2
WELL
POSITIONED?
Are
we well
positioned?
identify carina
chest radiograph
palpation of cuff
PHARMACOLOGY OF AIRWAY MANAGEMENT:
INDICATIONS
• facilitate a/w management
• reduce a/w trauma
• blunt rises ICP /IOP /MAP
• diminish airway reactivity
• reduce “stress” response
• facilitate transport / procedures
• humane considerations
PHARMACOLOGY OF AIRWAY MANAGEMENT:
CONTRA-INDICATIONS
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insufficient expertise
insufficient monitoring / equipment
insufficient personnel
during CPR
± hemodynamic instability
potential loss of airway
AIRWAY PHARMACOLOGY:
SEDATIVES AND ANALGESICS
DRUG
DOSE (mg/kg)
SIDE EFFECTS
fentanyl
0.001-0.003
n/v; hypoventilation
midazolam
0.05-0.15
hypoventilation, especially if
combined with opioids
propofol
1-3
apnea, hypotension,
painful injection
ketamine
0.5-2
apnea, secretions, ICP
lidocaine
1-1.5
AIRWAY PHARMACOLOGY:
AIRWAY
PHARMACOLOGY:
NEUROMUSCULAR
BLOCKADE
NEUROMUSCULAR BLOCKADE
DRUG
DOSE (mg/kg)
SIDE EFFECTS
succinylcholine
1-2
bradycardia,
hyperkalemia in at-risk pts
rocuronium
0.8-1.2
pain, precipitation with TPL
vecuronium
0.1-0.3
slow onset unless higher
dose
pancuronium
0.1
heart rate increase
slow onset and offset
atracurium
0.3-0.6
histamine release
slower onset
MANAGEMENT OF “FULL STOMACH”
• risk factors
 ingestion (delayed pain, stress, opioids)
 obesity, GERD
 esophageal pathology
• pharmacologic adjuncts
• airway management options
 awake intubation or tracheostomy
 rapid sequence induction (RSI)
RAPID SEQUENCE INDUCTION *
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metoclopramide and/or H-2 blocker (if time)
consider decompression gastric contents
denitrogenation (FiO2 1.0)
rapid IV induction with rapid onset NMB
 sux, rocuronium, high dose vecuronium
• Sellick’s maneuver
• apneic oxygenation vs. gentle PPV
• cricoid maintained until successful intubation
* RSI & CURRENT CONTROVERSIES COVERED
MORE FULLY IN A SEPARATE PRESENTATION
RAPID SEQUENCE INDUCTION HAS NO USE IN PEDIATRIC
ANESTHESIA (OPINION OF AUTHOR)
• lack of RCT’s to validate use despite potential harm
• almost impossible to avoid ventilation in small children
 low apneic threshold, high O2 demand, poor denitrogenation
• cricoid pressure inconsistently applied & best avoided
adequate force (if applied) may cause bucking, vomiting
airway often distorted; ventilation/intubation impossible
• dependent on personnel; OR and ER are very different
ENGELHARDT T. PEDIATRIC ANESTHESIA 2014;25:5
ENDOTRACHEAL INTUBATION (TI) IN PEDI ER
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TI a low frequency / high risk procedure
<0.1% pedi ER visits; 10x ↓ than adult ER visits
physiologic derangement, full stomach, low reserves
39% adverse events * (↓ BP, SaO2 most common)
•
first pass success 78% (49% w/out complication) *
• editorial: “proficiency”almost impossible → implications
for training and acceptable techniques **
* LONG E. PEDIATRIC ANESTHESIA 2014;24:1204
** LERMAN J. PEDIATRIC ANESTHESIA 2014;24:1199
CANNOT INTUBATE: BE PREPARED
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call for help
“best” laryngoscopy
multi-handed mask ventilation
LMA
emergency oxygenation
definitive (surgical) airway
emergency
cricothyrotomy
THE DIFFICULT AIRWAY: INTRODUCTION
IMPORTANCE OF RECOGNITION (RISK FACTORS)
• access
positioning (neck)
mouth opening
macroglossia
• visualization
micrognathia
• target
tumors, infection etc.